Explanation: Most would regard the Principate period of the Empire to be the height of Rome's power and prestige (here simply labeled as 'Roman Empire'), with the Eastern and Western Empires of the Dominate and Byzantine periods being in various states of decay.

The 'Holy Roman Empire', despite its name, was a MUCH later Medieval confederation of German states which often quarreled with the remnant state of the Byzantine Empire over who was the 'true' Rome. Despite my disgust for the Byzies, the Holy Roman Empire ain't even in the same ballpark as the Empire of old.